Recently, it has been argued that full-shell NWs [1]} threaded by a magnetic flux \(\phi =AB\) , with \(A\)  the cross-section of the nanowire and \(B\)  an external axial magnetic field, is a novel platform for realizing topological superconductivity [2]}. The full-shell geometry has the great advantage that a topological phase can be induced at known, and relatively low, magnetic fields; typically when \(\phi \)  is close to one flux quantum \({\phi }_0 = h/2e\)  (the precise range depending on the geometry of the full-shell NW [3]}). Experiments using InAs/Al full-shell NWs have reported on flux tunability of superconductivity, including full destruction and reemergence, owing to the Little-Parks (LP) effect [4]}, [5]}, [6]}. This LP effect is concomitant with zero bias peaks (ZBPs) in tunneling conductance, appearing in reentrant superconducting regions around \(\phi \sim {\phi }_0\) , which have been interpreted as MZMs [2]}. We use here similar InAs/Al full-shell NWs and investigate the role of the tunneling junction (green region of length X in Fig.  REFA) on the subgap spectra by performing tunneling spectroscopy measurements. Specifically, we use three experimental knobs, the magnetic flux, the junction length X and the global backgate voltage. Data from more than 40 devices verify that for \(X \lesssim 100 \, {nm}\) , the bare InAs NW acts as a tunnel barrier, while for \(X \gtrsim 150 \, {nm}\) , a quantum dot (QD) is formed in the tunnel junction region (data for intermediate lengths is not conclusive). The main text discusses data from five devices, which we refer to as A, B, C, D and E. Data from eight more devices are presented in the supplementary information (SI).
